HELP!! stopped laying

I have a chicken that is just under a year old. She lays blue eggs and has been giving anywhere from 3 - 5 eggs per week. The past month she hasn't laid 1 egg. She isn't acting sick. She looks better now then ever. she was missing all her back feathers from my other chickens peeking her but that has stopped all her feathers are back. She just won't lay a egg. She is out in the run so I don't think she is broody. These chickens are my first chickens so I have never had to deal with anything like this. I am so worried. The rest of my chickens are laying just fine. She is the only one that stopped. any ideal what is going on?